This invention relates to distillatory apparatus for distilling a liquid to purify it, to separate its components or to recover useful components from the liquid, and more particularly to distillatory apparatus of high distillation efficiency.
In conventional distillatory apparatus such, for example, as water producing apparatus for producing fresh water from sea water, the following construction is regarded as the most efficient. That is, an original liquid flows down in a filmy form on the surface of a pipe placed in a vertical direction and the pipe is disposed in a distilling chamber held under a predetermined atmospheric pressure and a plurality of such distilling chambers are provided in a vertical direction. In such a case, the atmospheric pressures in the distilling chambers are selected to gradually lower as the lowermost distilling chamber is approached. In order that evaporation may take place in the uppermost distilling chamber, a sufficiently heated original liquid is supplied to the uppermost distilling chamber and distilled liquids obtained from the respective distilling chambers are collected.
In such conventional apparatus, it is desired to increase the number of distilling chambers and to decrease the atmospheric pressure difference between adjacent ones of them for providing for enhanced efficiency in water production. To this end, if the length of the pipe of each distilling chamber is selected, for example, 2m and if the number of distilling chambers selected is 15, it is necessary to build a distilling column as high as more than 30m. The construction of such a high distilling column is very troublesome, time-consuming and costly. The original liquid supplied to each distilling chamber is supplied from the preceding chamber, that is, the original liquid supplied to the uppermost distilling chamber flows down into the subsequent ones one after another. Accordingly, it is necessary that the original liquid used be heated up to the temperature at which the original liquid can be evaporated in the uppermost distilling chamber, that is, up to the boiling point of the original liquid itself. However, the boiling point of the original liquid changes with the atmospheric pressure in each distilling chamber and becomes lower with a decrease in the atmospheric pressure. Therefore, in the conventional apparatus, the original liquid is heated up to the boiling point which is required in the uppermost distilling chamber, so that the original liquid supplied to the lower distilling chambers is once heated above the boiling-point temperature necessary for distillation in each distilling chamber. That is, useless heating is involved and this is the cause of lowering of the distillation efficiency.
Moreover, also in the conventional apparatus, the original liquid is heated by heat exchange between it and the distilled liquid obtained from each distilling chamber so as to provide for enhanced efficiency. However, when the distilled liquids from the respective distilling chambers are collected together, the temperatures of the distilled liquids are averaged, resulting in a large difference in temperature from the temperature necessary for the original liquid supplied to the uppermost distilling chamber. Accordingly, it is necessary that the original liquid once heated by the heat exchange be further heated appreciably. Further, according to the energy conservation law, the smaller the difference in amount between the two liquids to be heated exchanged becomes, the higher the heat exchange efficiency becomes. From this point of view, too, efficient heat exchange cannot be achieved with the prior art apparatus described above and the overall distillation efficiency is not enhanced. The water production efficiency of water production apparatus depends upon the quantity (cc) of distilled water obtained when about 540 cal. necessary for evaporation of 1 cc of water is applied to the water production apparatus. In the conventional apparatus, however, the water production efficiency is below 15 at the highest.
One object of this invention is to provide distillatory apparatus of high distillation efficiency.
Another object of this invention is to provide distillatory apparatus in which the number of distilling chambers can be easily increased.
Another object of this invention is to provide distillatory apparatus which is small in height and can be easily constructed at low cost in a short period of time.
Still another object of this invention is to provide a distilling chamber provided with a highly efficient heat exchanger.